January 20, 2011

The Most Important Book You Will Read This Year

Let me say this - my understanding is that this is a restated and simplified version of his 2007 tome, "Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health" (Chapter by chapter summary here). Read as a book on nutrition it is interesting. However, it is fascinating as a story of how science can run off the rails. Mr. Taubes does not attempt to politicize his views, but our national obesity epidemic can certainly be told as a story of an Epic Big Government Fail. Back in the 70's the political and medical establishments more or less united around the view that dietary fat was the cause of a national uptick in heart disease and obesity. Taubes makes a compelling case that the real culprit was (and is) refined carbohydrates and sugar.

For right-wingers who want more red meat, one can cast a bit of blame on hair-shirt environmentalists who noted (probably correctly) that an American diet high in beef and meat is not sustainable and achievable for the whole world. From the other side, lefties can cite Big Sugar, Big Corn (and its high fructose corn syrup) and Big Wheat as the enemy; why Big Meat and Big Dairy were outmuscled puzzles me.

The grim story is summarized very nicely in this LA Times article from last December. Some highlights:

Most people can count calories. Many have a clue about where fat lurks in their diets. However, fewer give carbohydrates much thought, or know why they should.

But a growing number of top nutritional scientists blame excessive carbohydrates — not fat — for America's ills. They say cutting carbohydrates is the key to reversing obesity, heart disease, Type 2 diabetes and hypertension.

"Fat is not the problem," says Dr. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health. "If Americans could eliminate sugary beverages, potatoes, white bread, pasta, white rice and sugary snacks, we would wipe out almost all the problems we have with weight and diabetes and other metabolic diseases."

Think about that - the obesity epidemic is estimated to cost America upwards of $100 billion per year, it may have been caused by a misguided government program in the 70's and we have an answer in sight! However...

It's a confusing message. For years we've been fed the line that eating fat would make us fat and lead to chronic illnesses. "Dietary fat used to be public enemy No. 1," says Dr. Edward Saltzman, associate professor of nutrition and medicine at Tufts University. "Now a growing and convincing body of science is pointing the finger at carbs, especially those containing refined flour and sugar."

Back in the 70's the government experts decided that dietary fat was the problem (eggs were bad, remember?). Now they need to redirect their message without grinding the gears, or their own credibility.

Let's detour through the science:

All carbohydrates (a category including sugars) convert to sugar in the blood, and the more refined the carbs are, the quicker the conversion goes. When you eat a glazed doughnut or a serving of mashed potatoes, it turns into blood sugar very quickly. To manage the blood sugar, the pancreas produces insulin, which moves sugar into cells, where it's stored as fuel in the form of glycogen.

If you have a perfectly healthy metabolism, the system works beautifully, says Dr. Stephen Phinney, a nutritional biochemist and an emeritus professor of UC Davis who has studied carbohydrates for 30 years. "However, over time, as our bodies get tired of processing high loads of carbs, which evolution didn't prepare us for … how the body responds to insulin can change," he says.

When cells become more resistant to those insulin instructions, the pancreas needs to make more insulin to push the same amount of glucose into cells. As people become insulin resistant, carbs become a bigger challenge for the body. When the pancreas gets exhausted and can't produce enough insulin to keep up with the glucose in the blood, diabetes develops.

Insulin signals the muscles to pick up blood sugar. However, it also triggers fat cells to do the same, and fat cells do not seem to become nearly as insulin-resistant as muscle cells. As the insulin system starts to break down the body become very good at storing excess calories as fat but not so good at releasing them.

As to what happens next in the public policy sphere, in the 2007 book Taubes explained that the nutrition establishment has had a hard time pivoting to a new message (I likened it to the battle between Galileo and Ptolemaic astronomy in this recent post.) However, the notion that sugar and refined carbs are a problem has a wide following. Harvard Medical School (home of the Dr. Willett quoted by the LA Times) recommends whole grains in preference to refined ones.

And there are many sources on paleolithic diets, where the logic is that we should eat what our forebears got by on for the first 500,000 years of human development and eschew this new-fangled stuff. I like Mark's Daily Apple, personally. And I should add that unlike Harvard, Paleos won't endorse grains, which are relatively modern.

What seems to be happening is that people are re-packaging the "refined carbs are bad" message in ways that don't directly flout the established "fat is bad" message.

BONUS BLOOD PRESSURE INCREASE: If science can go so awry on a topic such as our national diet, how much confidence do they deserve on a topic such as global warming, hmm? An obvious rejoinder would be "Waddya mean, 'they'? Surely these are different scientists using different tools and facing different issues". Well, yes, and stop calling me 'Shirley'.

I'm just pointing out that not all bubbles have been in finance, where the eventual market correction becomes blindingly obvious after the fact. As another example, we had a recent Greenpsan bubble - NO, not the hosuing bubble, and not the tech bubble - the bubble in belief that central bankers knew what they were doing.

Comments

Only clinical Harvard-educated retard could say that white bread and white rice are somehow different source of carbs than whole-grain or brown rice.

My understanding is that they do differ in terms of "glycemic load"--the impact on blood glucose levels. Not always a huge difference, but brown rice supposedly has about a 25% lower GL than white rice. I say this at the risk of being labeled a "Harvard-educated retard."

The two times I've actually done a full Atkins diet, I've gained a considerable amount of weight. However, cutting out sugar and increasing fiber has helped me -- not to lose weight, but at least to stop gaining it.

The only time I've involuntarily lost weight is when I had jobs where I was on my feet all day. Strict calorie-counting / portion control works, but I never can stick with it very long.

For someone who is trying to lose weight (not eat healthy but ONLY lose weight), is 200 calories from a sugary breakfast cereal exactly the same as 200 calories from a slice of wheat bread with some peanut butter on it?

is 200 calories from a sugary breakfast cereal exactly the same as 200 calories from a slice of wheat bread with some peanut butter on it?

My sense from reading about it is that the practical answer is "no," because 200 relatively empty calories will leave you wanting and needing more. Whether you care about the health aspect of it or not, the signals you will get from your body will push you to care. Even if it were strictly true that only calories matter (and I think that's not the case for reasons Taubes and others discuss), if you waste calories on junk you will more than likely end up consuming more overall.

rrsafety, here's a stab at it from my reading of Taubes and various related blogs:

The PaNu answer: chuck both breakfasts and use 200 calories of full cream in your coffee.
The nearly 100% animal fat will provide the energy you need, satiate hunger, and won't spike insulin.

Now, between the two breakfasts, the sugary one is likely worse. The glucose from the sugar and from the cereal (refined starch) will spike insulin. The fructose from the sugar (sugar = 1/2 glucose + 1/2 fructose) will convert in the liver to a ride for fats that get deposited in cells that the insulin spike opened up to receive fat.

The fat in the peanut butter will somewhat temper the glucose spike from the easily converted starches in the bread, and the combo of peanut butter and bread will have far less fructose for the body to deal with.

One result from either breakfast is that the insulin spike will cause you to be hungry later, so you will "need" to eat again - again, the sugary breakfast will make it worse due to bigger spike for the body to deal with.

I do it 2 days a week, and have managed to break the "couple of pounds a year" cycle I was on for 20 years.

I don't lose, but I'm not gaining either, and it's trivial: I eat breakfast on Tuesday and Thursday, and then eat or drink nothing with ANY calories until next morning. The other five days of the week, I eat whatever I want, including sitting on my ass watching a football game and stuffing my face with -horror of horrors!-... sugary drinks and SNACKS! Eating that way had me pushing 250 3 years ago.

I can't really say that I could lose weight by doing it every other day (the usual recommendation) but I'm pretty sure that I could. My 35# loss was accomplished the hard way - open heart surgery (my arteries are fine, had a bad valve), but it has kept it off.
I've managed to stay between 210 and 215 for two and a half years doing this.

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